After admission to the Coronary Care Unit 101 patients suffering from proved myocardial infarction were inquired about their prehospital phase. In the near future of the acute infarction the patients consulted their doctors more frequently. 73% had prodromi. The longest section of the prehospital phase was caused by the patient's decision time and the time between the call for help and the arrival at the hospital. However the transportation time was only 5% of the prehospital phase. Smoker's decision time was half that of non-smokers. Patients younger than 50 years had a longer decision time than patients of other agegroups. There was no differences in the prehospital phase for different days of the week, but the prehospital phase was longer at night than by day. To shorten the prehospital phase probably the best way is to cut down the decision time by medical advice and public information. In the case of the community of Hannover the advantages of a mobile coronary care unit are questionable.